RESEARCH ARTICLE Temporal Monitoring of Differentiated Human Airway Epithelial Cells Using

The airway epithelium is exposed to a variety of harmful agents during breathing and appro-priate cellular responses are essential to maintain tissue homeostasis. Recent evidence has highlighted the contribution of epithelial barrier dysfunction in the development of many chronic respiratory diseases. Despite intense research efforts, the responses of the airway barrier to environmental agents are not fully understood, mainly due to lack of suitable in vitromodels that recapitulate the complex in vivo situation accurately. Using an interdisci-plinary approach, we describe a novel dynamic 3D in vitromodel of the airway epithelium, incorporating fully differentiated primary human airway epithelial cells at the air-liquid inter-face and a basolateral microfluidic supply of nutrients simulating the interstitial flow observed in vivo. Through combination of the microfluidic culture system with an automated fraction collector the kinetics of cellular responses by the airway epithelium to environmental agents can be analysed at the early phases for the first time and with much higher sensitivity compared to common static in vitromodels. Following exposure of primary differentiated epithelial cells to pollen we show that CXCL8/IL–8 release is detectable within the first 2h and peaks at 4–6h under microfluidic conditions, a response which was not observed in conventional static culture conditions. Such a microfluidic culture model is likely to have util-ity for high resolution temporal profiling of toxicological and pharmacological responses of the airway epithelial barrier, as well as for studies of disease mechanisms